I already have all fruits except oranges and cherries and I don't know how to get them. I don't have Nintendo Online either, so that's out of the question. Is there a way to get all the remaining fruit?
You only get the other fruits from other players, either with nintendo online, or from friends, who then have to sit right next to you so that you can visit their island
No, it does not exist. You will only get the sister fruit of your starting fruit as well as coconuts and another fruit in a letter from Mama. The only way without an online membership would be that you meet with someone locally (= locally) and exchange ideas with him / her.